1. Field of the Invention
The present invention relates to a center pillar assembly of a motor vehicle, which is arranged between a front door and a rear door in such a way as to connect a roof and a floor with each other.
2. Description of the Related Art
In a conventional motor vehicle as shown in FIG. 1, a plurality of pillar assemblies 1 which are located on a left side and a right side of a vehicle body along a lengthwise direction of the body, function to support a roof 2 at a predetermined height from a floor and to hold front and rear doors 3 and 4 each of which is installed between two pillar assemblies 1.
Referring to FIG. 2, among the plurality of pillar assemblies 1, an example of a center pillar assembly which connects the roof 2 and the floor with each other between the front and rear doors 3 and 4, is illustrated.
As can be readily seen from FIG. 2, the center pillar assembly includes outer and inner panels 12 and 16 which are joined with each other in such a way as to delimit a closed space therebetween and connect the roof 2 and the floor with each other, and a reinforcing panel 14 which is disposed in the closed space defined between the outer and inner panels 12 and 16 in such a way as to reinforce rigidity of the center pillar assembly.
The outer panel 12 has an upper end portion 13 and a lower end portion which are integrated with a side frame of the vehicle body. The upper end portion 13 of the outer panel 12 is formed in a manner such that it projects outward and upward to correspond to a contour of an upper portion of the side frame. A flange portion which is formed on an upper end of the outer panel 12, is joined to a flange portion of a roof panel 32, which flange portion is formed on a side end of the roof panel 32.
The inner panel 16 is joined, below the roof panel 32, to a surface of a roof rail member 36 which is opposed to the upper portion of the side frame to delimit the closed space, and extends downward toward the floor. The inner panel 16 cooperates with the outer panel 12 to define the closed space.
As described above, the reinforcing panel 14 is disposed in the closed space which is delimited by the outer and inner panels 12 and 16, so as to reinforce rigidity of the center pillar assembly against external force.
Also, an anchor nut plate 19 for fastening a seat belt anchor nut is placed between the reinforcing panel 14 and the inner panel 16, adjacent to an upper end of the center pillar assembly.
In the center pillar assembly constructed as mentioned above, external force which is applied to the center pillar assembly upon side impact or the like, is absorbed by the reinforcing panel 14 which is disposed in the closed space defined between the outer and inner panels 12 and 16.
In this regard, because a head portion of an occupant is apt to be severely damaged upon impact in comparison with other portions of the human body and is very difficult to be restored to health, an upper part of a center pillar assembly must have excellent rigidity not to be deformed by side impact and thereby not to cause damage to the head portion of the occupant. In view of this consideration, the reinforcing panel 14 is formed, at an upper end thereof, with a stepped portion 15 which is bent toward the upper end portion 13 of the outer panel 12 in a manner such that rigidity of the upper part of the center pillar assembly is further reinforced.
However, in practice, even though the stepped portion 15 is formed on the upper end of the reinforcing panel 14, rigidity of the upper part of the center pillar assembly cannot be sufficiently increased in a manner such that the upper part of the center pillar assembly is not deformed due to side impact not to cause damage to the head portion of the occupant.